In the manufacturing process of semiconductor device, lithium battery, and the like, a dry room is used since atmosphere consisting of dry air with low dew point of lower than or equal to −50° C. is required. The dry room is equipped with a dehumidifier, where air exhausted from the dry room is fed to the dehumidifier and dehumidification process is performed by the dehumidifier, and the resulting dry air with low dew point is supplied from the dehumidifier to the dry room, so that atmosphere consisting of dry air with low dew point is uniformly maintained throughout the entire dry room.
In this case, in order to maintain uniform and constant atmosphere consisting of dry air with low dew point in the dry room, air with dew point of lower than the required level must be supplied to the dry room. Consequently, as the dry room grows larger, the airflow circulating between the dry room and the dehumidifier must be increased so as to supply a large amount of dry air with low dew point. To this end, a large and high-performance dehumidifier is required, which leads to a problem of increase of the installation cost and the running cost.
Almost all of moisture generated in the dry room is the moisture contained in air exhaled from the worker who works in the dry room, and, in the prior art, the moist air is dehumidified by the dehumidifier and again supplied to the dry room.
Thus, in the prior art, there is provided a method of directly exhausting moisture exhaled from the worker who works in the dry room to the outside of the dry room. According to one example of such conventional methods, a worker who works in the dry room wears a cover clothes, and air inside the cover clothes is sucked and exhausted to the outside of the room by an exhaust means. In this method, the air inside the cover clothes is exhausted from below the cover clothes, fed from an air intake provided on the floor of the dry room into an exhaust chamber, and exhausted to the outside of the dry room.
In this method, however, the worker always needs to stand at the air intake of the floor when the air inside the cover clothes is exhausted, so that the worker cannot freely move in the dry room. Furthermore, the air needs to be sucked from the air intake at a considerable wind speed in order to reliably take in the air exhausted from the inside of the cover clothes, whereby the running cost of an air blower therefor becomes high.
In addition, according to this method, the worker continues to be deprived of moisture of the body and becomes dehydrated in a short period of time, so that the worker cannot work in the dry room over a long period of time in consideration of health care of the worker.    Patent document 1: Japanese Laid-Open Patent Publication No. 11-287478